How to use two XL2411Z simultaneously?

Hey,

I bought a second XL2411Z and I dont know how to run both of them simultaneously @ 144Hz, since I only have one DVI port on my graphics card.

Specs: 2 x XL2411Z(p. monitor: D-sub + DVI-DL + HDMI x1)

Gigabyte Radeon HD7970(1xDVI, 1xHDMI, 2xminiDP)

(i5-3570k)

What would be the easiest way to run both monitors on 144HZ?

Thanks :)